c# - 在动态创建 PDF 之前显示加载屏幕

Question

我有一个 View ，即返回动态创建的 PDF，然后在新选项卡中显示 PDF，而不是返回 View()。我不会在任何地方保存 PDF，或将其存储在任何地方。我想做的是在创建 PDF 时显示加载屏幕。这能做到吗？

public ActionResult SolicitorActionReport_Load(SolicitorActionParamsViewModel viewModel) {
    var cultivationModel = new CultivationModel(viewModel, ConstituentRepository, CampaignRepository);
    var cultivationData = cultivationModel.GetCultivationActivityData();
    var reportParamModel = new List<ReportParamModel>
                                   {new ReportParamModel {AgencyName = SelectedUserAgency.AgencyName, StartDate = viewModel.StartDate, EndDate = viewModel.EndDate}};

    var reportToRun = "ActionDateCultivationReport";
    if (viewModel.SortActionBy == SolicitorActionReportSortType.Constituent) {
        reportToRun = "ConstituentCultivationReport";
    } else if (viewModel.SortActionBy == SolicitorActionReportSortType.Solicitor) {
        reportToRun = "SolicitorCultivationReport";
    }

    return FileContentPdf("Constituent", reportToRun, cultivationData, reportParamModel, new List<FundraisingAppealMassSummary>(), new List<FundraisingAppealPortfolioSummary>());
}



public FileContentResult FileContentPdf(string folder, string reportName, object dataSet,object reportParamModel,object appealMassDataSet, object appealPortfolioDataSet) {
    var localReport = new LocalReport();
    localReport.ReportPath = Server.MapPath("~/bin/Reports/" + folder + "/rpt" + reportName + ".rdlc");
    var reportDataSource = new ReportDataSource(reportName + "DataSet", dataSet);

    var reportParamsDataSource = new ReportDataSource("ReportParamModelDataSet", reportParamModel);
    var reportParamsDataSourceMass = new ReportDataSource("FundraisingAppealMassSummaryDataSet", appealMassDataSet);
    var reportParamsDataSourcePortfolio = new ReportDataSource("FundraisingAppealPortfolioSummaryDataSet", appealPortfolioDataSet);

    #region Setting ReportViewControl

    localReport.DataSources.Add(reportDataSource);
    localReport.DataSources.Add(reportParamsDataSource);
    localReport.DataSources.Add(reportParamsDataSourceMass);
    localReport.DataSources.Add(reportParamsDataSourcePortfolio);

    localReport.SubreportProcessing += (s, e) => { e.DataSources.Add(reportDataSource); };

    string reportType = "pdf";
    string mimeType;
    string encoding;
    string fileNameExtension;
    //The DeviceInfo settings should be changed based on the reportType             
    //http://msdn2.microsoft.com/en-us/library/ms155397.aspx             
    string deviceInfo = "<DeviceInfo><OutputFormat>PDF</OutputFormat></DeviceInfo>";
    Warning[] warnings;
    string[] streams;
    byte[] renderedBytes;
    //Render the report             
    renderedBytes = localReport.Render(reportType, deviceInfo, out mimeType, out encoding, out fileNameExtension, out streams, out warnings);

    #endregion

    return File(renderedBytes, mimeType);
}

Answer 1

I'm not saving the PDF anywhere, or storing it anywhere. What I would like to do is have a loading screen show up while the PDF is being created. Can this be done?

简答

不，不在新标签中。

---

您尝试做的事情的主要问题是您在控制浏览器方面缺乏能力。具体来说，当您告诉 anchor 在新选项卡中打开其超链接时(即 target="_blank")。有一些绕过这个问题的 hacky 方法通常只会让您的用户感到沮丧，因为您正在改变他们可能依赖/依赖的行为。

解决方法

使用此 jQuery File Download plugin 可以非常接近您想要的结果(view a demo)。基本上，它操纵一个 iframe 来排队下载。这使得显示正在加载的 div 成为可能，同时还能让用户保持在事件页面上(而不是将他们定向到另一个选项卡)。然后，用户可以单击最有可能在新选项卡中打开的已下载 PDF(查看兼容的浏览器 here)。

---

如果您决定使用此插件，请按照以下步骤进行应用:

1. Download插件 js 源并将其包含在您的 Scripts 中。

2. 包含插件 MVC 演示中提供的 FileDownloadAttribute 类:

   [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)] 
   public class FileDownloadAttribute: ActionFilterAttribute
   {
       public FileDownloadAttribute(string cookieName = "fileDownload", string cookiePath = "/")
       {
           CookieName = cookieName;
           CookiePath = cookiePath;
       }
   
       public string CookieName { get; set; }
   
       public string CookiePath { get; set; }
   
       /// <summary>
       /// If the current response is a FileResult (an MVC base class for files) then write a
       /// cookie to inform jquery.fileDownload that a successful file download has occured
       /// </summary>
       /// <param name="filterContext"></param>
       private void CheckAndHandleFileResult(ActionExecutedContext filterContext)
       {
           var httpContext = filterContext.HttpContext;
           var response = httpContext.Response;
   
           if (filterContext.Result is FileResult)
               //jquery.fileDownload uses this cookie to determine that a file download has completed successfully
               response.AppendCookie(new HttpCookie(CookieName, "true") { Path = CookiePath });
           else
               //ensure that the cookie is removed in case someone did a file download without using jquery.fileDownload
               if (httpContext.Request.Cookies[CookieName] != null)
               {
                   response.AppendCookie(new HttpCookie(CookieName, "true") { Expires = DateTime.Now.AddYears(-1), Path = CookiePath });
               }
       }
   
       public override void OnActionExecuted(ActionExecutedContext filterContext)
       {
           CheckAndHandleFileResult(filterContext);
   
           base.OnActionExecuted(filterContext);
       }
   }
   

   <子> github source

3. 将 FileDownload 属性应用于您的 ActionResult 方法:

   [FileDownload]
   public ActionResult SolicitorActionReport_Load(SolicitorActionParamsViewModel viewModel) {
       ...
   
       return FileContentPdf("Constituent", reportToRun, cultivationData, reportParamModel, new List<FundraisingAppealMassSummary>(), new List<FundraisingAppealPortfolioSummary>());
   }
   

4. 在您将链接到报告的 View 中包含必要的标记:

   <a class="report-download" href="/Route/To/SolicitorActionReport">Download PDF</a>
   

5. 将事件处理程序附加到 report-download anchor :

   $(document).on("click", "a.report-download", function () {
       $.fileDownload($(this).prop('href'), {
           preparingMessageHtml: "We are preparing your report, please wait...",
           failMessageHtml: "There was a problem generating your report, please try again."
       });
       return false; //this is critical to stop the click event which will trigger a normal file download!
   });
   

您可以在 http://jqueryfiledownload.apphb.com/ 查看工作演示.还有一个演示使用预先设置样式的 jQuery UI 模式来“美化”用户体验。

您还可以从 johnculviner / jquery.fileDownload 下载演示 ASP.NET MVC 解决方案github 以查看所有这些工作。